In contrast, a recent expert consensus suggests administering MMR and varicella vaccines at 12 months of age, if the following criteria are met: a CD4 count ≥400 cells/mm3, a CD8 count ≥200 cells/mm3, an adequate number of recent thymic emigrants (CD45RA), and a good response to the non‐live tetanus vaccine (antibody titer 3 weeks after the third dose of DTaP vaccine).21 The gene discussed is CD8A; the disease is chickenpox.